Telephone switching and busy-test apparatus.



' PATENTED. OCT. 23,-1906. J. G. WRAY, H. T. GARDNER & W. G. KINTON- TELEPHONE SWITCHING AND BUSY TEST APPARATUS APPLICATION FILED JULY3, 1905.

4 2 sums-anam- 1.

'flO 4 INVENTORS,

m *ATTTORNEK W am No. 833,906. g PATENTED 001 23, 1906.

J. G. WRAY, H. T. GARDNER & W. G. KINTON.

TELEPHONE SWITCHING AND BUSY TEST APPARATUS.

APPLIOA'LIONIILED JULY3,1906.

2 SHEETS-SHEET 2.

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ULTJ @UEw I I mi /w; W W V ATTORNEY.

' I INVENTOk; I

1 UNITED STATES PATENT orricn.

JAMES GQ WRAY, OF oHIo-A o, HERBERT T. GARDNER, or MAYWooD, AND WILLIAM G. KINTON, OF onIoAGo; ILLINOIS, AssIGNoRs TO Busy-Test AMER'IcAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORA- 'IION OF NEW YORK.

TELEPHONE SWITCHING no. es aeoc; 1 I

' siding at Chicago, HERBERT T. GARDNER, re-

siding at Maywood, andWILLIAM vGr. KINTON, residing at Uhica o, in the county of Cook, State of Illinois,- liave invented certain Improvements in Telephone Switchin and Apparatus, of which the fol owing is a specification. Y

The present invention relates to telephoneexchange systems, and is shown as comprised in a trunk-line switchboard apparatus for connecting one central station with-another or substation-lines converging to one central station with-those centering at another, the principalfeature of the invention consisting In an automatically-operating busy-test system and appliances for the multiple part of ,said trunk-hne switchboard apparatus in as sociation with an automatic signaling system for the wanted substation, the operator at the calling central station being, moreover, notified if the line wanted is busy-by the automatic operation of a busy-back signal. I The system is further so arranged that single-partylines or selective twosparty lines may be signaled, the lines of both classes heingequipped with multiple jacks or jacks at each sectlon of the multiple switchboard and the two-party lines being also provided with two jaoks-that is, one for each of its stations at the several multiple-switchboard sec-.

tions. The calling system is automatic, so

that it is only necessary for the operator at the called central station to insert the plug in the proper jack in order (provided the line of such jack be not already engaged) to signal A the desired subscriber.

The system, is so ar ranged that it is impossible .to signal any sub 'scriber until the properconnection has been actually made at both centralstations, the

final connection and giving of the signal tle= pending upon the operation of a main ay at the called central station, such operation, however, being de endent upon such conditions as to insure t e proper connections be-' fore thesignal has been given. 'The busy-, back-signal to the call-originating station also depends for itsultimate o 'eratlon upon this relay, the back contact 0 an armature controlled .by said relay maintainin a eucuit which previously had been close by an- 7 Specification of Letters Patent. Application filed July 3, 1905. Serial llo. 268,214.

ANQD BUSY-TEST APPARATUS.

Patented Oct. 23, 1906,

other relay and u on which the aforesaid sig nal depends, wln e the conditions are such that the relay cannot attract its armature if the line is busy. The operation ofthe main relay is controlled by shunt-circuits of sufficiently low resistance to short-circuit the resaid shunt-circuits being controlled by a relay which depends for its 0 eration upon the insertion of the plug at t e calling central station, while the other-depends upon the actionof a relay controlled by the insertion of the plu at the called central station, so that one ort e other, or both, of said shunts will be closed around the main relay pending the insertion of both plugs in; the jacks. The giving of the signal further depends u on the operation of the main relay at'the called central station, and thesaid relay cannot operate until both shunts have been opened, so that it is impossible'to give a premature signal or to give s signal at all in the case ofan error in the assignment of the trunk-line. The main relay, furthermore, is influenced by a special circuit which is so arranged as to "prevent the operation of the relay if the line called for is busy, this circuit being so arran ed that if the-potential of the battery is on t 1e line both terminals of the relay will be connected to the same terminal of the battery and both terminals of the relay connected also with the opposite terminal of the battery through substantially or approximately equal resistances, whereby the magnetizing eilect is substantially balanced, so

lay and prevent the operation thereof, one of Y i that suflicient,magnetism cannot be devel 0 ed to attractv the arm ature. The giving of t e signal on the line wanted is, under these conditibns thus revcnted, while the busyback signal is p aced inoperation, and the calling subscriber and the "calling operator thereby notified that the line is busy.

Figure 1 is a diagram of the circuits at the calling central station Fig. 2 is a diagram of the circuits at the called central station,

said figure also showing the answering and calling jacks and multiple representatives 1 of the latter for a one-party line and a twoparty line. big. 3 is a diagram illustrating too the battery GOIIIICQlJlOl'lS when a plug has been Inserted into a ack belonglng to a busy line, and Figs. 4 and 5 are details showing mechanical expedients for operating the circuit-controllers in a manner necessary to insure the necessary operations.

The salient features of the invention are mainly illustrated in Fig. 2; but certain of the circuits extend through both central stations, and in tracing such circuits it is to be understood that the conductors indicated by After the operator at the calling subscribers centra station (which will-be hereinafter designated as station M) has been signaled in the usual way and has ascertained the desires of the calling subscriber the said operator inserts the plug B in the jack B,

which corresponds to the trunk-line L hav- -ing main conductors b b, which has been assigned, the operator having previously by means of the circuit L having conductors a and a asked the operator at the called central station (hereinafter designated as station N) to assign the trunk to be used, and

stated to the latter operator the number of the station wanted.

Assuming that station N o. 500, Fig. 2, on a single-station line is the station wanted, the operator at the central station N insertsthe p ug G into the jack 0 and if conditions are normalthat is to say, ift'he o erator at the station M has placed the plug in the-jak B and the line leading to station 500 is not busya signal will be given at the'said station, which signal will be stopped upon the taking down of the receiver. i p

. The operations of producing the signal and stopping the same form no part of the pres- 'ent invention, and it is sufficient to state that under the conditions hereinbefore outlined a circuit is closed from the generator through the'condenser and bell at the station, the said circuit includin the main coil e of'relay e and winding 51 o the inductioncoil I, so that the bell is rung and an audible signal repeated back to the calling-stations, the said signal being stopped upon taking down the receiver at station 500, which by shunting the bell and condenser causes an increased-flow of current through the relay 6, so that the armature of said relay will be attracted, thereby breaking-the signaling-circuit. The completion of the signaling-circuit, however, oe ends upon theoperation of the relayfiwhic 'relay is subjected to control, so that it will fail to operate unless the plugs at both central stations M and N have been placed in their a propriate jacks, and if the called or wanted ine is busy. For this purpose the main relay f, which is in a circuit primarily closed by the connection of the sleeve C of plug 0 with the frame or socket C of the jack C is rovided with shunt-circuits of sufiiciently ow'resistance to prevent the,operation of the relay so lon as the said shunts remain closed, two 0 these circuits depending, respectively, upon the operation of relays controlled, respec: tively, by the plugs at the oppositeends ofthe trunk-line, there being also a third circuit, which is capable of'influencing the relay f and preventing the operation thereof when the wanted line is busy. Under normal conditions if the wanted lineis not busy and both plugs have, been inserted in their respective jacks the relay d,f Fig. 2, will have been energized by current in a circuit which may be traced as follows: battery D, conductor 1, conductor 2, conductorB, the winding of said relay d, conductor 4, winding 50 of the induction-coil I, conductor 1), jack-spring G, 'thence'returning to ground G g and thus to the other terminal of the-battery.

The armatures d and d of the relay d'will therefore .be-attracted'"or moved to a posh.

tion the reverse of that" shown in Fig. 2; A'"

circuit will also be closed through'the relays f and m and the coil e of relay e, which-may be traced as follows:. Starting from the bat roe .tery D, the circuit passes through the conductor 6, coil e winomgff relay m, winding of relay f, sleeve Cf, jac tor 7, cut-off relay h, conductors 8 and 9 to ground G and thence back through ground G to the other side of the battery D. Under normal conditions the relays f and m will attract their armatures, so that thesaid armstures will be in the position opplpsite that shown in Fi 2 of the drawings, w le'the coil e of the reay e will r'nagnetize the core of -frame 0 conduca said .relay sufiiciently to retain the armature (2 thereof attracted after the exalted action of the main coil 6 due to the taking down of the receiver at the called substation. ing-circuit is then closed from thetip. of the plug to its ring through conductor 10, armature f conductor 12, induction-coil windin 51, to the battery and from the other termina ofthe battery through induction-coil winding 52, supervisory relay 7', armature e, conductor 13, armature f and conductor 14. The final I completion of this circuit, however, dependsupon the energization of t e coil e of the relay e, which, as previouslstated,

The talk-.,

takes place upon the removal of the receiver at the called substation, this feature requiring no further explanation, since it does not enter into the present invention.

' In order to prevent the operation of the rerelays mand (1, there being, first,a' closed shunt around the relay{; up to the time that both the plugs-B and U ave been inserted in the jacks, and, second, a closed. circuit througha suitable resistance which is capa:

' ble of influencing the relay f if the line Wanted is busy.

For convenience 'in description these cir-- cuits will be hereinafter referred to as shunt X, shunt Y, and special circuit Z, these reference characters, howevennot being placed upon the drawings, since; they are merely used for thepurpose of distinguishing the circuits in the description,

, 1 relay 2. 39.

The shuntX, which's controlled by the re-- lay d, extends through conductor 15, back contact of relay (1, armature d", and conductor 16 to'the conductor 6, which leads t'othe battery and forms part of the usual circuit controlled by. the sleeve and frame, the main circuit including the relays f m and coil 0 of The shuntX thus afiZords a low resistance path around the relay f, through which prior to the operation of the relay d the relay f isshort-circuited, the result being that the said relay is thus far not energized and does not attract the armatures f 2 and f Since, therefore, the relay d is controlled by the operator at the station M, the signaling and talking circuits, which are finally controlled bythe relay 1, cannot be closed priorto the insertion of the plug B in the proper trunk-jack B at station M.

, I The shunt Y extends through the conductor 15, conductor 17, armature m of relay m,

and conductors 18 and 16 to the conductor 6, thus making a second short circuit around the relay f in addition to that of the shunt X.

This circuit is controlled by the armature 'm of the relay mfwhich relay being included in -the main sleeve andrframe-circuit becomes energiz'ed'upon insertion of the plug O m the jack C, it being obvious, therefore, that the relay'f willnotoperate until the plug C has been placed in'position. 4

So far as relates to the prevention of a premature signal or false signal in case of a wron 'trunkassignment the shunts X and Y allor the necessary protection; but these shunts by themselves will not operate to prevent thegiving of. the signal and the final connection of the two substations if the wanted line is busy.

To revent the operation of the relay f in case t e wanted line is busy, the special circuit Z is employed, and before tracing this circuit in Fig. 2 reference may be had to Fig.

'3, which shows in a simple. diagram the conunites t ditions existing if the plug C is laced inthe jack C of aline whic is alrea y connected elsewhere, as by the plug 0 inserted in.

jack C lof said line at another section of the Y multiple switchboard. In this case it will be seen that one terminal of the battery D will be connected through the coils of the rela. s e and m to one end of the relay f, while t e same terminal of the battery is connected through the corresponding relays e,'m, and f of the busy line associated with the cordcircuit ofjplu 0 to theoppositeterminal "of the relayl f t ough the conductor 7, which circuit being controlled by the operation of several jack-framesof the same. i

the relay f itself if the said relay :is free to operate. 0?, m, and f of the cord-circuit terminating in switchlug 0, through which it is sought to establis connection with a Wanted-line, are

. of course the same as those of the co lesponding relay-coils e, m and oftlie cord circuit of plug C through which a connec-' tion has previousl wanted line, establishing the busy condition of the same, and arevso roportioned to the special resistance r and t e resistance of the cut-off relay that if the line called for is bus .a similar potential is established at The resistances of the relay-coils been made wi h such" bot terminals of the relayf, which accordingly will not operate and the signal will not be given nor the line connection completed.- Starting with the conductor 6, Fig. 2, which is connected with one terminal of the relay f, the special circuit may be traced through conductor 16, armatured the forward contact of said armature; conductor 19, armature f of relay f, conductor 20', which includes the resistance r, conductor 21, armature m of relay m, and conductor 22 to the ground at G", thus connecting-one terminal of relay f with the ground, the same terminal being connected with the other of thebattery through the coil 6 of the relay e and the coil of relay m. The'opposite terminal of rela f is grounded in the usual way through tli conductor 7, and cut-ofi relayhand if the lineis busy is also connected with the other terminal of the battery through the jack,

pole

e plug-sleeve, jack frame,

plug, and associate-relayed", m ",andf at the section of the multiple switch Where a.

previous connection has been established with the, wanted line. Under these condition's', therefore,;there isia balance of, potn mally open at m and=also at (i becoming closed at-m upon the insertion of the plug G into its. jack and at d upon the insertion of the plug B. The operations of these relays,

however, as previously described, vcut out the shunts X and Y, and in order to prevent the operation ofthe relay f if the line is busy the armature m which controls the special circuit Z, is arrangedjto reach its back con- 1 tact before the armature m, which controls the shunt Y, has opened the said shunt, the armature d, which controls the shunt X, o crating in the same way, so'that one or t e other. of'said-shunts is momentarily closed at the same time that the special circuit is closed, thereby insuring the short-circuiting of the relay f if the line wanted is busy.

. ductors 12 23-24 and armature m of relay m, whichis then in engagement with its for:

ward contact, and thereby connected with conductor 26. The busy-backssignal-produc- 1 ing apparatus, which is indicated "as a rotat- 'tion, making it desirable for the operator at 'ingrnember s, having a ring s and a commutator or rotary circuit-interrupter s is suppliedwithcurrent through con uctors 27 and 128 and conductors 24 and 23, the inductioncoil winding 55 being inthis circuit. The removal of the plug 0 breaks the busy-back circuit by releasi'n the armature m. As herein shown, the re aymma be further rovided with .an armature m ,w 'chcon ro s the ordinary busy-test circuit and-n10 e of operation, which may be utilized, if desired, in'case there ares'everal lines leading toone substastation N to test inde endentl of the operdrawing the plug C.

the-end of the said spring 18101 at station M. Ot erwise t e operator at N, being-warned by the lighting of the usual lamp-signal that the operator at M has, view of the busy condition of the wanted line, withdrawn the plug B, disconnects by with- Fig's. 4 and 5' illustrate details showing racticable devices for controllin the circuits Y, and Z in the manner descr bed to close one circuit before another is broken. In Fig. 4 the, armature d of the relay d is shown as provided with a. springd, connected with conductor 16 and having sufficient play to remain in contactwith the conductor15 until is engaged by-the overhanging arm d?! of e armature, which constitutes a'conductor to connect conductor 16 with conductor 19, after which the final movement of thearmature separates the sprin d fromconductor. -15.-

. In ig. 5 thearmature of the relay m is shown as provided with two spring-contacts m andm, corresponding, respectively, to

the separate armatures m and m (shown in Fig; 2,) one of said-springs m having sufficient play to remain 1n engagementwith the conductor 17 until after the other s ring m has made engagement with the con uctor 21, thus obtaining substantially the same result. As illustrated in Fig. 2, the system hereinbefore described is applicable to use with a selective two-party line, the control of the signaling being provided for by the engagement of the springs in multiple spring-jacks, there being one signal-bell branched to ground from one side of the line and another signal-bell branched to ground from the other side of the line, this system requiring-no further detailed description, since it forms no part ofthe present invention.

It is to be understood, of-course, that the drawing is a conventional illustration of the system, the relays being shown where the controlof two ormore circuits is involved as pro- .vided with twoor more armatures. In practice" each relay may be and usually is provided with a single armature adapted to actuate such contacts as may be necessary forthe control'ofthe several circuits.

In order to avoid any possibility of misunderstanding, it may bestated that the lower? most jack )1? of each set of jacks shown in the drawings is the anSWeringack'for the line to which it belongs, the operation of said answeringjacks not being referred to, since no novelty is involved, the jacks being shown simply to complete the illustration of the system in genera at we claim is 1'. Ina telephone system for connecting two central stations, a relaycontrolled by the plug and jack at the calling central sta tion; a'rela controlled by the plug and jack at the calle central station; a third relay to control the main connecting circuit from one central station to the other; and shunt-circuits around said-third relay controlled respectively by the other two relays.

2'. In a telephone signaling s stem, a signaling-circuit a relay to contro said circuit; a source of current; a conductor'which con-.- nects one terminal of said'source of current to one. terminal of said relay; multiple jacks; a conductor or ground connection to connect said jacks with the other terminal of said source of current; means for connecting the opposite terminal of said relaywith any one 0 said jacks; a conductor to connect the first-named terminal of the relay with the second-named terminal. of the source of current; means controlled by said relay for controlling a circuit including said conductor; and one or more sega'rately controlled shuntcircuits around sai relay.

3. In a telephone signaling s stem, a signaling-circuit; azrelay to controfsaid circuit; a source of current; a conductor which consecond-named terminal "of the'source of ourrent; means controlled by said relay for con-- trolhng aacircuit" including said conductor; zone or more separatelymontrolled shunt-cirto one terminal of said relay; multiple jacks;

a conductor or ground connection. to connect said acks-with the other terminal of said: source of current; means for connecting the;

oppositeterminalof said relay with any one o said.jacks;-.a conductor to connect the first-named terminal of the relay with the *cuits around-sald relay; .one or'more circuitcontrollers; and means whereby the said circontrollers in a circuit including-said conduc tor, the said shunt-cireuits around jsaid relay being also under control of the said circuitwit-controllers operate to'close said circuit includingsaid conductor before opening said shunt cireuits;

In a" telephone system -for; timing-lines, a main'relay to control the sig-' J naling and talkingcircuits'; a shunt-circu1t' I around said relay-Mia ted toibe' opened by the insertion of thiep uglin the jack at the z's 'callmg1 -'cuit a apted to be opened by the insertion-of central station; a second shunt eir f the plug atthe called central station';-'a'-spe-,

. j jack a switc thereof, and adapted to o erate and to close said circuit when, the sai plugbeing inserted in said-jack, thejline connected-with. said jackLis disenga ed; "and means for establish- :ing substantia 4b I (ysimilar potentials at both termin'als'of sai relay,. and for thereby preventing its 0' ration onthe insertion of the.-

plu' when t e-li'ne connected with said jack 1s a ady occupied; substantially as set forth.

automatic busy-test system .arid' apparatus eomprising'amulti le switchboard; a switch-plu and main and local conductors associated t erewit'h; a test-circuit uniting. the frame-pieces of the'several jacks of a line and adapted to be com leted throughthe local-circuit conductor 0 i said plug; a relay connected withjsaid local-circuit conductor and controlling the said mainecireuit conductors; and means for either' establishing an operative eurrentthrough-saidrelay; or es- 1 tablishin 'substantiall similar potentials at both 0 the termina s thereof, whenthe said switch-phi is placed in aspr'ing-jaek of H any line; aeeor g assaid line is athbert-y or I already busy; substantially as set forth. 7 v

In testimonywhereof weh'ave signed ;-our names to this speeification, in the :presenceof two subscribing witnesses,- this 28th day-of June, 1905.

JAMES ewRu.

HERBERT T. GARDNER. 7

WILLIAMG KINTON Witnesses: a MARION A. RE'EvE, GEonoE E. CnIPMAN. 

